1. Field of the Invention
The present invention finds application in the textile field and relates to a draw frame with a main control and at least one auxiliary control and to a method for the operation of a drafting arrangement according to the apparatus as claimed.
Various devices and control devices for the comparison of fiber slivers are known, which are based on the principle of the drafting of the sliver. As a fuel, the slivers, doubled in a two-stage drafting process, are compared in a break draft and a main draft. Within the framework of the drafting process, with which several slivers are normally doubled at the same time, the aim is the production of a fiber sliver which is as homogeneous as possible. In the appropriate draw frame, slivers with irregularities or disturbances on the entry slide should be gathered together on the output side as a sliver with a predetermined cross section which is as uniform as possible. This requirement implies a control of the drafting process. The most widely different drive arrangements which decal with this problem exist at the existing state of technology as well as feed back and control devices.
Problems arise with the existing developments of driving arrangements and devices. The disturbances and fluctuations caused by the drive were certainly taken into account through known controls. To be sure, it was shown that consideration of the appropriate disturbances in the framework of a single main or total control required compensation in a very large control range, which demanded too much from conventional devices. At the same time, a disadvantage lay in that the total calculation load was concentrated and time dependencies of the controls were not optimized.